[Melas]

No, there won't be any studies that show that 70mph uses less than gas than 55mph. Simple physics is enough to demonstrate to even the most stuborn of village idiots that drag is exponential.

[stevio]

Drag may be exponential but an engine is most efficient at it's maximum torque output. My wife owned a '91 4runner that got ~21mpg @ 70mph as opposed to ~19mpg @ 55mph. The net torque on that engine occurred at 2800rpms(70mph). I believe that to be true on most vehicles as most vehicles have overdrive.